Two-temperature refrigerating system



May 24, 1949. L. w. ATCHISON 2,471,137

TWO-TEMPERATURE REFRIGERATING SYSTEM I Filed April 22, 1947 Inventor-z Leonard w Atchison,

by 61%;, 1', m

His Attorney Patented May 24, 1949 TWO-TEMPERATURE SYS York

REFRIGERATING TEM Leonard W. Atchison, Erie, Pa., assignor to General Electric Company, a corporation of New Application April 22, 1947, Serial No. 743,015

6 Claims.

1 My invention relates to refrigerating apparatus and more particularly to refrigerating systems including a plurality of evaporators for operation at different temperatures.

Refrigerators are sometimes provided with two compartments which are maintained at substantially different temperatures, one ofthe compartments being suitable for the storing of frozen foods and the other being used for general food preservation. These two compartments may be cooled by separate evaporators, and in such case it is necessary to maintain the evaporators at different temperatures in accordance with the requirements of the separate compartments. It is desirable to arrange the refrigerating system for automatically controlling the supply of refrigerant so that the refrigerating capacity of the apparatus will be concentrated on the evaporator requiring it. Accordingly, it is an object of my invention to provide a two-temperature refrigerating system employing two evaporators and including an improved arrangement for maintaining the evaporators at different temperatures.

It is another object of my invention to provide an improved two-temperature refrigerating system including two evaporators in series wherein provision is made for automatically diverting refrigerant from one of the evaporators.

It is a further object of my invention to provide an improved two-temperature refrigerating system including two evaporators in series wherein provision is made for concentrating the full refrigerating capacity on one of the evaporators.

Further objects and advantages of my invention will become apparent as this description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

For a better understanding of my invention reference may be had to the drawing, the single figure of which shows a schematic representation of a two-temperature refrigerating system including an embodiment of my invention.

Referring now to the drawing, the refrigerating system includes a compressor I, a condenser 2, a low temperature evaporator 3 and a higher temperature evaporator 4. The two evaporators are connected in series relationship. Liquid refrigerant from the condenser 2 is supplied to the evaporators through a capillary tube 5. Vaporized refrigerant is withdrawn from the evaporators through a suction line 8, which is connected to a header I of the evaporator 3.

In order to provide for the control of the flow of refrigerant to the evaporators, the capillary tube 5 is connected to a housing 8 of a solenoid control valve. One end of the housing is placed in communication with the low temperature evaporator 3 through a conduit 8 and the opposite end of the housing is connected with the higher temperature evaporator 4 through a conduit II]. The housing is provided internally with a valve seat I I at one end and a second valve seat I2 at the opposite end. Within the housing there is provided a valve or flow-controlling element I3, which includes tapered ends arranged to cooperate with the valve seats II and I 2. The valve I3 is provided with one or more longitudinal grooves I4 in order to allow passage of the refrigerant entering the housing through the capillary tube 5 to either the conduit 8 or the conduit I0.

In order to control the position of the valve I3 a coil I5 is arranged about the exterior of the housing 8. The coil is energized from any suitable source of power through lines I8 and I'I,'and the supply of electrical energy to the coil is controlled by a switch I8. In order to govern the operation of the switch a thermostatic bulb l9. which is responsive to the temperature of the higher temperature evaporator, is placed in communication with a bellows 20 to move the switch to. the open and closed positions.

The higher temperature evaporator 4 is arranged in series with the low temperature evaporator 3 through a constant back pressure valve 2 I, which is adapted to maintain a predetermined pressure in the evaporator 4 and to open for allowing flow of refrigerant to the low temperature evaporator 3 when this pressure is exceeded.

This valve includes a housing 22 which is provided with a valve seat 23. A valve member 24 is arranged within the housing for cooperation with the valve seat 23 to control the flow of refrigerant. The position of the valve member 24 is governed by a bellows 25 which is arranged 'within the housing and is secured to the valve I member 24. A spring 28 is arranged about the valve member 24 in order to bias the valve toward its open position. In order to provide for adjustment of the pressure to be maintained by the valve a second bellows 21 is provided on the exterior of the housing 22. An adjusting screw 28 is threaded into a bracket 29, which is secured to the housing 22, and the screw bears against the bellows 21. In order to provide for communication between the internal bellows 25 and the external bellows 21 a passage 30 is provided in the housing 22. Thus the pressure exerted by the internal bellows 25 in maintaining the valve against its seat may be adjusted by the screw 28. The compressor I is driven by an electric motor 3| or any other suitable source of motive power. Electrical energy for the motor 3| is supplied from any suitable source of power through lines 32, 33. In order to control the starting an stopping of the compressor in accordance with the temperature of the low temperature evaporator a thermostatic bulb 34 is arranged to be responsive to the temperature of the evaporator 3. This bulb 34 is connected by a tube" to a bellows 36. The bellows 36 controls the opening and closing of a switch 31, in accordance with the temperature indicated by the thermostat bulb 34.

The operation of the system is as follows: The apparatus is shown in the drawing under conditions wherein the higher temperature evaporator is below its predetermined maximum temperature. Under these circumstances the switch It; is open and the coil I is deenergized. The valve I3 is positioned by gravity in engagement with the lower valve seat l2. This blocks the flow of refrigerant to the higher temperature evaporator 4 and provides communication from the capillary tube 5 through the conduit S to the low temperature evaporator 3. Should the temperature of the higher temperature evaporator 4 increase to its predetermined maximum, the switch It closes in response to the temperature indicated by the thermostatic bulb l9, and electrical energy is supplied to the coil IS. The energization of the coil l5 causes the valve ii to move upwardly and engage the valve seat I I. This movement of the valve blocks the flow of refrigerant from the capillary tube 5 directly to the low temperature evaporator 3, and opens the passage from the capillary tube 5 through the conduit ID to the higher temperature evaporator 4. At a predetermined pressure within the evaporator 4 the valve 2l opens and refrigerant is supplied through the evaporator 4 to the evaporator 3. Thus under these circumstances refrigerant is supplied to both the evaporators in series. When the temperature of the evaporator 4 has been reduced to its predetermined minimum the switch l8 opens, deenergizing the coil l5 and allowing the valve [3 to resume its gravity-influenced position in engagement with the valve seat l2. This results in positively directing the liquid to the low temperature evaporator 3 without passing through the evaporator 4. When the low temperature evaporator 3 has reached its predetermined minimum temperature the switch 31 opens, cutting off the electrical energy to the motor 3| and stopping the operation of the compressor.

. In the apparatus described above it can be seen that I provided an arrangement whereby liquid refrigerant is positively directed either to the low temperature evaporator alone or to the two evaporators in series. This arrangement enables the full refrigerating capacity to be concentrated on 4 the low temperature evaporator at such times as refrigeration is not required by the higher temperature evaporator. Since no refrigerant flows through the higher temperature evaporator during such periods, this arrangement offers the further advantage that the higher temperature evaporator may be more readily operated on a defrosting cycle, since the temperature thereof can readily rise above 32 F. during these periods. Furthermore, the interposition of the constant back pressure valve between the higher temperature evaporator and the low temperature evaporator controls communication between these two evaporators so that the evaporators may be maintained at. different temperatures.

While I have shown a particular refrigerating system embodying my invention I do not desire my invention to be limited to the specific details shown and described and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a refrigerating system including condensing apparatus and two evaporators, a liquid line for conducting refrigerant from said condensing apparatus, and a temperature controlled valve disposed in said liquid line for controlling the flow of refrigerant to said evaporators, said valve being responsive to the temperature of one of said evaporators for positively directing said refrigerant to the other of said evaporators alone to the exclusion of said one of said evaporators or to both of said evaporators in series.

2. In a refrigerating system, a low temperature evaporator, a higher temperature evaporator, a valve for positively directing liquid refrigerant to said evaporators in series or to said low temperature evaporator alone to the exclusion of said higher temperature evaporator, and means responsive to the temperature ofsaid higher temperature evaporator for controlling said valve.

3. In a refrigerating system, a low temperature evaporator, a higher temperature evaporator, a valve for positively directing liquid refrigerant to said evaporators in series or to said low temperature evaporator alone to the exclusion of said higher temperature evaporator, means responsive to the temperature of said higher temperature evaporator for controlling said valve,

3 and a second valve disposed in the line between said evaporators for maintaining a predetermined maximum pressure in said higher temperature evaporator.

4. In a refrigerating system including condensing apparatus and two evaporators, a liquid line for conducting refrigerant from said condensing apparatus, and a temperature controlled valve disposed in said liquid line for controlling the flow of refrigerant to said evaporators, said valve being responsive to the temperature of one of said evaporators for positively directing said refrigerant to the other of said evaporators alone to the exclusion of said one of said evaporators or to both of said evaporators in series, a conduit between said evaporators for conducting liquid and vaporized refrigerant from said one of said evaporators to said other of said evaporators, and a second valve disposed in'said conduit for maintaining a predetermined maximum pressure in said one of said evaporators.

5. In a refrigerating system including a liquid line .and a suction line. a low temperature means for supplying refrigerant to said higher temperature evaporator and then to said low temperature evaporator in series, and a solenoidoperated valve disposed in said liquid line and operated in response to a predetermined minimum temperature of said higher temperature evaporator for positively directing the refrigerant to the low temperature evaporator to the exclusion of said higher temperature evaporator,

6. In a refrigerating systemincluding condensing apparatus and two evaporators operating at different temperatures, a liquid line for conducting refrigerant from said condensing apparatus,v a solenoid-operated thermostaticallycontrolled valve for directing liquid refrigerant from said liquid line to the higher temperature evaporator and to the lower temperature evapo- LEONARD W. ATCHISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,005,860 Huntington June 25, 1935 2,198,328 Brown et a1 Apr. 23, 1940 Hoesel Nov. 11, 1941 

